On the optimization of solar-driven refrigerators

The thermodynamic optimization of a solar driven refrigerator, that is, a refrigerator driven by use of the solar Rankine power cycle, is studied in this paper. The system is totally irreversible, i.e. externally and internally irreversible. The effect of the operating conditions on the overall efficiency of the system is evaluated.     

Hydrogen consumption and power density in a co-flow planar SOFC

In the present work, power density and hydrogen consumption in a co-flow planar solid oxide fuel cell (SOFC) are studied according to the inlet functional parameters; such as the operational temperature, the operational pressure, the flow rates and the mass fractions of the species. Furthermore, the effect of the cell size is investigated. The results of a zero and a one-dimensional numerical electro-dynamic model predict the remaining quantity of the fed hydrogen at the output of the anode flow channel. The remaining hydrogen quantities and the SOFC's power density obtained are discussed as a function of the inlet functional parameters, the geometrical configuration of the cell and several operating cell voltages values.     

Electricity consumption and economic growth,the case of Lebanon

In this paper we investigate the causal relationship between electricity consumption and economic growth for Lebanon, using monthly data for Lebanon covering the period January 1995 to December 2005. Empirical results of the study confirm the absence of a long-term equilibrium relationship between electricity consumption and economic growth in Lebanon but the existence of unidirectional causality running from electricity consumption to economic growth when examined in a bivariate vector autoregression framework with change in temperature and relative humidity as exogenous variables. Thus, the policy makers in Lebanon should place priority in early stages of reconstruction on building capacity additions and infrastructure development of the electric power sector of Lebanon, as this would propel the economic growth of the country.     

Analysis of the polypropylene mechanical behaviour response: Experiments and numerical modeling

The security requirements in the industrial world incite an ever deeper understanding of the behaviour and the fracture of polymeric materials used as structural parts of the passenger compartment. We are looking at a polypropylene commonly used in this field in order to identify the physical processes responsible for their mechanical properties. The mechanical characterization of the response of the polymer under simple and complex strain relies on a unique method of combining performing numerical analysis techniques. The behaviour of polypropylene with large deformations dissipative involves several processes. Its consequences on the mechanical properties of materials are significant. The analysis of these results to emphasis that the plasticity of the polymer involves addition mechanical properties. Taken together, these observations can lay the groundwork for a thermodynamic modeling of the behaviour law to this class of polymer. The contribution of this approach was demonstrated by experimental and numerical modeling of the polypropylene mechanical behaviour.     

Application of coulped code method for the analysis of VVER-1000 coolant transient benchmark

In the light of the sustained development in computer technology, the possibilities of code capabilities have been enlarged substantially. Consequently, advanced safety evaluations and design optimizations, which were not possible few years ago, can now be performed. Nowadays, it becomes possible to switch to new generation of computational tools, namely, coupled code (CC) technique. The application of such method is mandatory for the analysis of transient events where strong coupling between the core neutronics and the primary circuit thermal-hydraulics exits, and more especially when asymmetrical processes take place in the core leading to local space-dependent power generation. Through the current study, a demonstration of the maturity level achieved in the calculation of 3-D core performance during complex accident scenarios is emphasized. The study is followed by a typical application through which the main features and limitations of this technique are discussed.     

Experimental study of combustion performances and emissions of a spark ignition cogeneration engine operating in lean conditions using different fuels

This work presents an experimental study describing a six-cylinder spark ignition engine running with a lean equivalence ratio, high compression ratio, ignition delay and used in a cogeneration system (heat and electricity production). Three types of fuels; natural gas, pure methane and methane/hydrogen blend (85% CH₄ and 15% H₂ by volume), were used for comparison purposes. Each fuel has been investigated at 1500 rpm and for various engine loads fixed by electrical power output conditions. CO, CO₂, HC, and NOx emissions values, and exhaust gas temperature were measured. The effect of fuel composition on engine characteristics has been studied. The results show, that the hydrogen addition increased HC emissions (around 18%), as well as performance, whilst it reduced NO_x (around 31%), exhaust gas temperature, CO and CO₂.     

Synergistic effect of graphene and carbon nanotube on lap shear strength and electrical conductivity of epoxy adhesives

In this study, synergy between graphene platelets (GnPs) and carbon nanotubes (CNTs) in improving lap shear strength and electrical conductivity of epoxy composite adhesives is demonstrated. Adding two-dimensional GnPs with one-dimensional CNTs into epoxy matrix helped to form global three-dimensional network of both GnPs and CNTs, which provide large contact surface area between the fillers and the matrix. This has been evidenced by comparing the mechanical properties and electrical conductivity of epoxy/GnP, epoxy/CNT, and epoxy/GnP-CNT composites. Scanning electron microscopic images of lap shear fracture surfaces of the composite adhesives showed that GnP-CNT hybrid nanofillers demonstrated better interaction to the epoxy matrix than individual GnP and CNT. The lap shear strength of epoxy/GnP-CNT composite adhesive was 89% higher than that of the neat epoxy adhesive, compared with only 44 and 30% increase in the case of epoxy/GnP and epoxy/CNT composite adhesives, respectively. Electrical percolation threshold of epoxy/GnP-CNT composite adhesive is recorded at 0.41 vol %, which is lower than epoxy/GnP composite adhesive (0.58 vol %) and epoxy/CNT composite adhesive (0.53 vol %), respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48056.     

Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na₂SO₄ solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.     

Substrate heterostructure effects on interface composition,microstructure development and functional properties of PZT thin films

Platinum- and (La_0.8,Sr_0.2)MnO₃ (LSMO)-terminated silicon substrates were used for the liquid-phase deposition of Pb(Zr_0.52,Ti_0.48)O₃ (PZT) thin films. Different layer thicknesses ranging from 100 to 600 nm were processed by sequential coating. Characterization of the films involved X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy (XPS) combined with depth profiling to probe the interface composition. The films deposited on Pt exhibit an intermetallic layer, Pt_xPb, after annealing at 500 °C in air. This film has been used to establish the XPS signature of the intermetallic phase which consists of a negative shift of the peak position of Pt(4f) due the electron transfer from Pb to Pt. In all cases pure phase perovskite thin films were obtained after short annealing at 700 °C. XPS depth profiling shows unambiguously the existence of an intermetallic layer, Pt_xPb, of approximately 10 nm at the interface between Pt and PZT, while an interdiffusion layer of ～30 nm was observed between LSMO and PZT. The impacts of interfacial layers on microstructure development and functional properties translate in the formation of specific textures, i.e. a pronounced (1 1 1)-texture on Pt due to lattice matching between (1 1 1)-PZT and (1 1 1)-Pt_xPb, and a random film orientation on LSMO, and a substantial thickness dependence of the dielectric and ferroelectric properties, though specific behaviors were observed for the two different substrate heterostructures.